At present, the 3rd generation partnership project (3GPP) proposes the concept of licensed-assisted access (LAA), which uses an unlicensed spectrum with the help of a licensed spectrum of long term evolution (LTE). However, when a LTE network uses an unlicensed band, it is necessary to ensure that a LAA system can coexist with related access technologies (such as Wi-Fi) on a fair and friendly basis. However, in the traditional LTE system, there is no listen before talk (LBT) mechanism to avoid collision. In order to coexist with the Wi-Fi, a LTE system needs a LBT mechanism. In this way, if it is detected that a channel is in a busy state on the unlicensed spectrum, the LTE system cannot occupy the band. If it is detected that the channel is in a clear state, the LTE system can occupy the band.
Based on the above problems, a LBT mechanism of load based equipment (LBE) is proposed in the related art. The LBT mechanism of the LBE is cycle-free. As long as a service arrives, a clear channel assessment (CCA) is triggered.
For uplink transmission of the LAA system, since the uplink transmission is based on scheduling, if an uplink grant (UL grant) is transmitted in a subframe n, then the scheduled user equipment (UE) may transmit uplink data in a subframe n+i by using a resource block (RB) indicated in the UL grant.
Since the uplink transmission of the UE in a subframe n+4 is performed based on the UL grant transmitted by a base station in the subframe n, if uplink LBT is based on a load, it is not clear when the scheduled UE starts uplink CCA, i.e. how to configure a starting point of the uplink CCA time of the scheduled UE received the UL grant.